gstreamer/samples/AppSrc.cs

/*
 * AppSrc.cs: example of using the appsrc element
 *
 * Authors:
 *   Maarten Bosmans <mkbosmans@gmail.com>
 *
 * Copyright (C) 2009 Maarten Bosmans
 *
 */

using System;
using System.Runtime.InteropServices;
using GLib;
using Gst;
using Cairo;

public class AppSrcDemo
{
	static MainLoop loop;
	static Gst.App.AppSrc appsrc;
	static Pipeline pipeline;

	public static void Main (string[] args)
	{
		Application.Init();
		loop = new MainLoop();

		// Construct all the elements
		pipeline = new Pipeline();
		appsrc = new Gst.App.AppSrc("AppSrcDemo");
		Element color = ElementFactory.Make("ffmpegcolorspace");
		Element sink = ElementFactory.Make("autovideosink");

		// Link the elements
		pipeline.Add(appsrc, color, sink);
		Element.Link(appsrc, color, sink);

		// Set the caps on the AppSrc to RGBA, 640x480, 4 fps, square pixels
		Gst.Video.VideoFormat fmt = (BitConverter.IsLittleEndian) ? Gst.Video.VideoFormat.BGRA : Gst.Video.VideoFormat.ARGB;
		appsrc.Caps = Gst.Video.VideoUtil.FormatNewCaps(fmt, 640, 480, 4, 1, 1, 1);

		// Connect the handlers
		appsrc.NeedData += PushAppData;
		pipeline.Bus.AddSignalWatch();
		pipeline.Bus.Message += MessageHandler;

		// Run, loop, run!
		pipeline.SetState(State.Playing);
		loop.Run();
		pipeline.SetState(State.Null);
	}

	static void PushAppData(object o, Gst.App.NeedDataArgs args)
	{
		ulong mseconds = 0;
		if (appsrc.Clock != null)
			mseconds = appsrc.Clock.Time / Clock.MSecond;
		byte[] data = DrawData(mseconds);

		Gst.Buffer buffer = new Gst.Buffer(data);
		appsrc.PushBuffer(buffer);
	}

	// Returns a byte[] presentation of one 640x480 BGRA frame using Cairo
	static byte[] DrawData(ulong seconds)
	{
		Cairo.ImageSurface img = new Cairo.ImageSurface(Cairo.Format.Argb32, 640, 480);
		using(Cairo.Context context = new Cairo.Context(img))
		{
			double dx = (double) (seconds % 2180) / 5;
			context.Color = new Color(1.0, 1.0, 0);
			context.Paint();
			context.MoveTo(300, 10 + dx);
			context.LineTo(500 - dx, 400);
			context.LineWidth = 4.0;
			context.Color = new Color(0, 0, 1.0);
			context.Stroke();
		}

		byte[] data = img.Data;
		img.Destroy();
		return data;
	}

	static void MessageHandler(object sender, MessageArgs args)
	{
		Message message = args.Message;
		string text = String.Format("Message from {0}:  \t{1}", message.Src.Name, message.Type);
		switch (message.Type) {
			case MessageType.Error:
				Enum err;
				string msg;
				message.ParseError(out err, out msg);
				text += String.Format("\t({0})", msg);
				break;
			case MessageType.StateChanged:
				State oldstate, newstate, pending;
				message.ParseStateChanged(out oldstate, out newstate, out pending);
				text += String.Format("\t\t{0} -> {1}   ({2})", oldstate, newstate, pending);
				break;
			case MessageType.Eos:
				loop.Quit();
				break;
		}
		Console.WriteLine(text);
	}
}